The shooting of an arrow from a bow has been the subject of study, prompted to a large degree by the difficulty for an archer to consistently place an accurate shot. This difficulty is due largely to the many variables involved in shooting an arrow with a bow. Many problems associated with learning to shoot accurately stem from the fact that the "system" for shooting the arrow includes not only the bow and arrow but also the archer. Each archer is different, and the shooting position for an archer will inevitably vary some from shot to shot, resulting in inconsistent effects on the accuracy of each shot.
Among the factors of an archer's shooting position that affect accuracy is a consistent draw. The draw not only affects the range, by the draw length, but also the direction of the flight of the arrow by the direction of the draw. Accordingly, successive draws of the arrow must be pulled back in the same direction and to the same distance from the grip for consistent shots. Many archers attempt to achieve some consistency by use of an anchor or "nock point". An anchor point is a point on the archer, usually the face, such as a cheek, nose, tooth, a point on the lip, etc., to which the archer will draw the string. However, this may not ensure consistently accurate shots. If, for example, the archer changes the position or angle of his head from shot to shot, this may change the position of anchor point and the direction of the draw, which will affect the direction of arrow flight.
Another factor affecting accuracy is the way in which the archer holds the grip on the riser. If the archer "torques," i.e., applies a moment about the vertical axis of the riser by an improper grip, this moment will be translated into a slight rotation of the bow. This rotation will force the ends of the bow limbs to one side, which in turn puts a lateral force on the base of the arrow when it is released. This lateral force will drive the back of the arrow to one side as it leaves the bow. Torque can be difficult to detect, since the archer can properly draw the arrow to the anchor point and aim the arrow, but inadvertently apply a torque on the bow. In addition, only a small torque is necessary to adversely affect shot accuracy. Since the only indication of torque is the slight rotation of the bow at the riser and the slight displacement of the bow limb ends, and the rotation is often small, torque cannot normally be perceived by the archer.
Often a marker or "button" on the string is used as a reference to bring the archer to a consistent anchor point when the bow is drawn, e.g., by bringing the button to the nose. In addition, peep sights are frequently used to assist in providing a good anchor point, as well as provide an aiming device. A peep sight is mounted on the string and comprises an aperture, such as provided by a device with a small aperture placed in the strands of the string, through which the archer can peer while the bow is drawn. Although these devices, particularly when used in combination with each other, can help in achieving a consistent anchor point, they provide no means for detecting torque, and thereby minimizing torque to the riser. In addition, a peep sight with a small aperture is most effective for aiming and anchor point alignment; but such a small aperture renders the sight difficult or impossible to use in low-light situations, such as early morning or late dusk. Furthermore, the peep sight is directly in the view of the archer when sighting, obstructing his view, which compounds the difficulties in low light conditions. In addition, the peep sight and button must be changed every time the string is changed. When this happens, the archer must adjust or "recalibrate" his shooting position to compensate for the unavoidable, although slight, change in position of the peep sight and button. This adjustment, which is both a physical and psychological adjustment, results in the archer not achieving his normal accuracy until he becomes accustomed to the new string.
In additkion to peep sights, there are various sights in the prior art that are used to sight the arrow. While variations in the archer's position can to some extent be determined by use of these sights, they either do not detect both anchor-point and torque problems, or they cannot distinguish between them. For example, for some sights with the arrow drawn to an improper anchor point, the archer may see some misalignment, but the same symptom may be caused by torquing, which, from the view of the archer, shows the same or similar misalignment in the sight. The archer is then unable to determine whether to compensate for the misalignment by changing the anchor point or by changing torque on the grip. In addition, the archer may be able to align and aim with the sight, while applying a torque and using a misplaced anchor point. In this case, even though the bow is perceived by the archer as properly drawn and aimed, the shot will not be accurate. Thus, without the ability to determine torque and anchor-point displacement independently from each other, the archer cannot know whether he is attaining a consistent shooting position by using these prior art sights.
Another problem with many prior-art sights is that while some can be adapted to detect torque, they cannot detect a small torque. Even a very slight torque on the riser, for example, caused by changing the position of the fingers, or opening or closing hand grip, can affect the flight direction of the arrow. These slight changes in torque are usually so slight and cause such a small displacement of the sight, that the displacement is not easily perceived by the archer.
Another problem with some prior-art sights is that they replace the normal sights on the bow and require that the archer relearn his sighting technique using a new type of sight. Archer's frequently use a sighting pins placed on a mounting bracket extending from the riser, with several sighting pins provided for different ranges or shooting distances. To aim, the archer aligns the appropriate pin with the target. Sighting pins can be used with peep sights, but many sights, particularly reflecting sight, replace or supersede conventional reference-type sights, such as sighting pins.
Another problem is that some sights are bulky and complex, which decreases the durability of the sight. This allows the sight to be easily damaged or knocked out of alignment, as compared to conventional reference-type sights. Particularly for those reflecting sights that are mounted in place of sighting pins, a bow with a damaged or misaligned sight will be without a working sight and totally useless to the archer.
A further problem with many sights, particularly with most reflective sights with multiple reflected images and with a light path through a narrow housing or aperture, is that they are difficult or impossible to use in low light conditions, such as early morning, or late dusk. This can be a severe handicap to bow hunters who frequently hunt under these conditions.
U.S. Pat. No. 3,320,670 to Ambraziatis discloses an archer's bow sight comprising a reflection means that reflects an image of the arrow tip to the archer and an alignment means connected to the reflecting means for aligning the arrow in relation to a target. The alignment means and reflection means are positioned such that the tip of the arrow is reflected by the reflection means with the image of the tip covered by or aligned with alignment means. The bow is aimed by aligning the alignment means on the target and the reflected tip image. The sight may be lowered to raise the trajectory of the arrow or adjusted to the left or right to compensate for windage. The adjustments are empirically determined by the archer after a number of test shots, and adjustment has to be made for each range. (col 3, lines 63, 64, and 73 to col. 4, line 2; col. 4, lines 23 to 31). While the Ambraziatis sight may show some bow and archer misalignment, it is very insensitive to detection of torque because the displacement of the arrow due to torquing is not great. In addition, since the arrow point is close to the reflection means, a small displacement due to torquing or to an anchor point misplacement would probably not be perceived by the archer.
U.S. Pat. No. 3,715,807 to Heffer discloses a bow sight comprising a mirror to reflect an image of the arrow to the archer with a sighting means attached to the mirror to align with a target. The preferred sighting means is a vertical filament against the mirror face extending into the target picture. When the image of the arrow is centered in the mirror, the flight of the arrow will lie in the vertical plane, which contains the arrow centerline and vertical cross-hair. A blade is moved along the length of the filament in the target picture to adjust for range. The bow is aimed by aligning the target with the crossed filament and blade. This sight is also inadequate in detecting and distinguishing bow misalignments, and sometimes may contribute to poor shooting position. If the bow is torqued, the displacement of the arrow in the bow is very small, and its image is too close to the mirror for the displacement to be practically perceived by the archer. In addition, a change in range is accomplished with this sight by moving the bow/arrow combination with respect to the aiming eye, which requires that the archer change his anchor point for each range. Thus, this sight requires the archer to change his shooting position from shot to shot, and, therefore, prevents the archer from developing a correct shooting position which is used consistently from shot to shot. An object of the Heffer sight is to provide a sight that is independent from the physical characteristics of the archer, which requires the archer to adjust his shooting style to fit the sight, instead of permitting the archer to shoot with his most comfortable style. Another problem with this sight is that the surface of the arrow is a poor reference for showing small misalignments, as the arrow axis would have to have a large misalignment to show a perceivable deviation of the arrow image from the center of the mirror.
U.S. Pat. No. 2,001,470 to Nyvall discloses a bow sight of the "periscope-type" comprising an upper and lower mirror on a generally vertical alignment. The image of the target is reflected from one mirror to the other which reflects the image to the archer. The lower mirror is lined or reticulated, such that the arrow is aimed by aligning the image of the target on the lines of the lower mirror. (page 3, col. 1, lines 14 to 49) An inherent problem with periscope-type sights is that they have the inability to independently indicate and distinguish between torque and anchor point problems. For example, torquing or a misplaced anchor point will both show a misalignment of the sight, with no indication to the archer of the proper corrective measures to take to assume a correct shooting position. In addition, since the mirrors are close together, and particularly since only one mirror is marked with reference points, only a large misalignment from torque or anchor-point misplacement would be perceivable by the archer through the sight. Another inherent problem with the periscope sights is that one must aim through a double mirror system, which can clutter the view of the archer as he sights on the target, adding visual confusion and diminishing the ability of the archer to quickly assess the target and the flight path of the arrow. In addition, under low-lighting conditions, the double reflected image of the target image may be difficult to see through the sight rendering the sight impossible or difficult to use.
U.S. Pat. No. 3,524,440 to Hill discloses another periscope-type archer's bow sight comprising an upper and lower mirror, with cross-hairs or an equivalent aligning device mounted on one of the mirrors. The mirrors are aligned vertically forward of the bow. The lower mirror is focused on the target, while the upper mirror is focused in the lower mirror and reflects the target image to the archer's eye. The mirror with the cross-hairs may be adjusted to compensate for distance and windage. The Hill bow sight is designed primarily to compensate for distance and windage and requires adjustment each time the distance or windage change. Hill discloses that the position of axis of the mirrors ahead of the bow allows the archer to perceive changes in torque by observing the mirrors. While torque will misalign the mirrors from the archer's viewing perspective, so will anchor-point problems, so that this sight has the same inherent problems of all periscope-type sights. Therefore, even when the Hill sight is aimed and aligned, it does not ensure that the bow/archer position is correct.
U.S. Pat. No. 4,979,309 to Oligschlaeger discloses another periscope sight with a target image mirror and a fixed reflected image mirror adapted for range finding. An aiming point is linked with the target image mirror such that the reflected image of the target and the actual image of the target can be placed in vertical alignment. The bow is aimed by placing the aiming point over actual image of the target while in this vertical alignment. The sight compensates for differing distances when adjusted and allows the archer to shoot at an unknown distance. The alignment device uses a cam apparatus and requires different cams for different archery equipment and archers. However, this sight is much like the Hill sight above, and accordingly suffers from the same inherent problems of periscope-type sights, particularly the inability to independently determine and distinguish anchor-point and torque problems.
Other periscope-type sights in the art are described in U.S. Pat. No. 4,507,874 to Brown, U.S. Pat. No. 4,178,693 to Smith, and U.S. Pat. Nos. 4,646,444, and 4,733,474 to Cary. While these sights may have improved adjustment and range-finding abilities and may be easier for an archer to use than other such sights, they all have the inherent problems of periscope-type sights.
Besides the problems of the above prior-art sights of not adequately indicating misalignments in the archer's shooting position, many suffer from the problem of being too bulky, too heavy, or unwieldy. This is particularly true for bow hunting where the shooting conditions are usually not ideal, and the archer may have to move and shoot quickly. In addition, any bow accessory should preferably permit the parallel use of sights that the archer has normally on the bow, such as the conventional multiple range pins. This allows the archer to shoot in a manner in which he is accustomed without the necessity of learning new or elaborate sighting techniques. In addition, this allows for a backup system if the device is damaged or misaligned by allowing use of the bow with its normal sights without the device.